Physics (Theses and Dissertations): Recent submissions
Now showing items 281-300 of 458
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Purification and electrical characterisation of nanotube and nanowire - polymer composites
(Trinity College (Dublin, Ireland). School of Physics, 2006)The yield and purity of multiwalled carbon nanotube (MWNT) soot was maximised by control of production parameters. The optimal production parameters were found to be J = 190 A/cm2 and P = 500 Torr achieving a yield of up ... -
Linear and nonlinear optical characterisation of silicon nanowire structures
(Trinity College (Dublin, Ireland). School of Physics, 2008)The morphological and optical properties of various silicon nanowire structures were investigated. Photoluminescence was produced by all of the nanostructures and was attributed to a variety of different mechanisms. Optical ... -
Investigation of near-infrared laser diodes for application in space-based spectroscopic gas sensing
(Trinity College (Dublin, Ireland). School of Physics, 2007)The availability of numerous semiconductor diode lasers that provide wavelength tuneable, high output power, single frequency emission in the near infrared region of the spectrum (0.7μm - 2.5μm) provides researchers with ... -
Dispersion and characterisation of carbon nanotube and MoSI nanowire composites
(Trinity College (Dublin, Ireland). School of Physics, 2007)Recently, composites of polymers with various one-dimensional nanoparticles, mainly carbon nanotubes, have been investigated to develop robust electrically and thermally conductive materials or for mechanical reinforcement. ... -
Interface properties of Fe3O4/MgO and surface studies of Fe3O4(110)
(Trinity College (Dublin, Ireland). School of Physics, 2006)The research project described in this Ph.D. thesis can be divided into two parts. The first, consisting in the description of a new instrument, the low temperature tunneling device (LTTD), designed and built in order to ... -
Instrumentation and techniques in confocal microscopy
(Trinity College (Dublin, Ireland). School of Physics, 2007)Liquid crystal variable focal length microlenses are designed, fabricated and tested for inclusion into the confocal system. Their emerging light fields are imaged and examined. This proves a novel, efficient and thorough ... -
Fabrication and characterisation of chemical vapour deposition grown branched carbon nanotube arrays
(Trinity College (Dublin, Ireland). School of Physics, 2007)The fabrication, optimisation and characterisation of arrays of straight and junction multiwall carbon nanotubes (MWNTs) is presented in this thesis. A detailed description of the design and fabrication of the chemical ... -
Optical characterisation of blue-green-emitting polymer gain media : light amplification, laser emission, and two-photon absorption
(Trinity College (Dublin, Ireland). School of Physics, 2006)Blue-green emitting stilbene dyes have been incorporated into different inert polymer hosts. Steady-state absorption and emission spectroscopy revealed a considerable host dependence of the spectroscopic properties of these ... -
Surface studies of Fe3O4(001), Fe/Ge(001) and Fe3O4(001)/Ge(001)
(Trinity College (Dublin, Ireland). School of Physics, 2006)This work consists of surface studies of three systems; firstly, the (001) surface of a Fe3 O4 single crystal, secondly, the initial nucleation of Fe on the Ge(001) surface, and finally, iron oxide formed on Ge(001). The ... -
Computational modelling of novel permanent magnetic designs
(Trinity College (Dublin, Ireland). School of Physics, 2005)Moderm permanent magnetic materials provide unique design opportunities as their low susceptibility makes them effectively transparent to external magnetic fields. This also simplifies the calculation of magnetic fields ... -
Magnetism in dilute magnetic oxides and related materials
(Trinity College (Dublin, Ireland). School of Physics, 2007)The work in this thesis is focussed on the magnetic properties of dilute ferromagnetic semiconducting oxides and related materials. Since the first report of unexpected room temperature ferromagnetism in anatase and rutile ... -
Disks around weak-line T Tauri stars
(Trinity College (Dublin, Ireland). School of Physics, 2006)The formation of low -mass (M ~ 1 M⊙) stars has generally been divided into four stages before reaching the main sequence: Class 0 (cloud of gas and dust) -> Class I (embedded star with disk in envelope) -> Class II (visible ... -
Optical characterisation and manipulation of active microspheres
(Trinity College (Dublin, Ireland). School of Physics, 2007)Spherical microcavities are of great interest for both photonic applications and for fundamental physics. In this thesis, a novel active dielectric microsphere emitter coated with colloidal CdTe nanocrystals is studied. ... -
Electron-hole excitations and optical spectra of rare gas solids
(Trinity College (Dublin, Ireland). School of Physics, 2004)This thesis is a theoretical study of the optical and dielectric properties of semiconductors and insulators. The quantity that defines the relationship between measurable optical properties and electronic structure of ... -
Synthesis and properties of a novel carbon nanotube-polymer thin film composite
(Trinity College (Dublin, Ireland). School of Physics, 2006)A novel method for carbon nanotube-polymer composite production is demonstrated in this thesis. The technique presented provides a way in which the position of nanotubes within a polymer matrix can be controlled. By ... -
Two-photon-absorption in semiconductor micro-cavities
(Trinity College (Dublin, Ireland). School of Physics, 2006)In this thesis a study of two-photon absorption photoconductivity in semiconductor microcavities is presented. It can be shown that a 10,000-fold enhancement of the non-linear two-photon absorption response can be obtained ... -
Spin valves and their application
(Trinity College (Dublin, Ireland). School of Physics, 2006)The discovery of giant magnetoresistance (GMR) in the late 1980's resulted in massive interest in the deposition and characterisation of artificial layered magnetic structures. Spin valves were discovered in 1991 and have ... -
Optical and electrical characterisation of hexabenzocoronene derivative molecular self-assemblies
(Trinity College (Dublin, Ireland). School of Physics, 2006)In this thesis the optical properties of molecular aggregates of Hexa-peri-benzocoronene derivatives are investigated for evidence of Frenkel Exciton Resonance (FER). Using photo-luminescence and optical absorption measurement ... -
Electrodeposition of coercive ferromagnetic films
(Trinity College (Dublin, Ireland). School of Physics, 2005)The need for even more compact and low power consumption devices has been the driving force for microeiectromechanical systems (MEMS). Also the integration of MEMS into current state of the art silicon technology has set ... -
MgO-based magnetic tunnel junctions and their applications
(Trinity College (Dublin, Ireland). School of Physics, 2008)Massive research has been carried out on magnetic tunnel junctions (MTJs), which consist of two ferromagnetic layers sandwiched by a thin insulating barrier, since they were first discovered in 1970. The electrode resistance ...
